As computers and telephones become more and more integrated, a new technology has evolved referred to as computer telephony integration (CTI). Computer telephony integration may be defined as the functional merging of telephony and data processing services in order to add value to business or other service applications. More specifically, CTI permits an exchange of command and status information between voice and data processing environments. The telephony system is typically a private branch exchange (PBX) but could be a telephone line established for a single line business connected to a computer. The data processing system may range from a large mainframe computer to a small, personal computer.
CTI architectures include complex combinations of both hardware and software systems. A simple architecture requires only a direct link from the phone to an external adapter that connects to a PC serial or parallel port. Users can have direct control over call routing so that to transfer a call, the user just clicks on an icon and the PC sends a message to the switch emulating a command from the phone requesting that the switch transfer the call. A server-based architecture connects a telephone switch to a server on a local area network (LAN). The LAN server, rather than the switch or user, is responsible for routing calls. In PBX-based computer telephony integration, a common CTI channel is provided between the computer system and the PBX telephone system (the PBX is connected to the public telephone network). Each user is viewed as a CTI client having a PC or workstation connected to a local area network. Each user also has a separate telephone that is connected directly to the PBX. There is no physical connection between the individual workstations and telephones.
CTI protocols have been developed to permit the computer and telephone systems to communicate. More formally, a CTI protocol is a set of messages and associated sequencing rules for communicating at application layer 7 of the OSI model between the computer and telephone system. Many of these CTI protocols are proprietary or closed and do not allow for application internetworking across PBX platforms. Attempts have been made to provide open CTI protocols, the most successful of which is the Computer Supported Telephony Applications (CSTA).
CTI software applications enable computers to manipulate the telephone domain as well as the data/computer domain. A simple CTI application is a telephone directory application that maintains a catalog of names, addresses, company details, and telephone numbers, wherein those numbers can be selectively and automatically dialed in the CTI computer. A more sophisticated CTI application is automatic call distribution to route a large number of telephone calls to telephone agents based on data instructions in a call center computer. An application programmer interface (API) allows an application program residing in a computer to invoke certain telephony actions and enables development of new applications while protecting existing software. The API decouples various applications from the underlying platform such as a PBX control platform.
There is a long felt need to efficiently and effectively provide and coordinate telecommunication services for an organization or other types of subscriber groups located in different geographical locations. Such organizations, businesses, and groups of subscribers also need advanced telecommunications service functions like internal/private numbering plans, automatic call distribution, personal telephone support where telephony functions are invoked by a user interacting with his computer terminal, customer support services where data is displayed on a computer terminal to assist in the current conversation, special applications for institutions like hotels, schools, etc., data accesses to switch supported and computer supported databases, and so on.
Attempts have been made to address these problems by public telephone operators using central telephone switching office equipment as well as by private networks using dedicated Customer Premise Equipment (CPE). CPE solutions are typically constructed around a private branch exchange which either itself possesses basic control functionality or is controlled by an external application server connected by a CTI data link. Within this CPE-based environment, a variety of different proprietary application servers using computer-based protocol to control the PBX may be used. For purposes of this application, this wide range of application servers is encompassed generally by the term CTI server. Applications running on a CTI server may be used for services such as routing of incoming calls to an idle agent in an automatic call distribution environment, handling display of messages, rerouting functions, multiple party calls, etc.
A significant advantage of CPE-based systems using PBXs and CTI servers is that new and customized service features may be quickly and relatively inexpensively developed and provided. Still, there are a number of drawbacks with PBX-CTI server solutions. For example, a CTI server can only control those telephone extensions in a private telecommunications network which are associated with the private network's PBX. At a business level, private networks require that a customer purchase, install, and maintain telephony switching equipment at the customer's premises. Further, variations in capabilities and protocols between different PBX manufacturers make it difficult to "mix and match" private network features designed by one manufacturer for its PBX for use on another manufacturer's PBX. Even if there is support for networked PBXs controlled by a single CTI server, there is significant limitation in the functionality that may be offered across two or more PBXs. Of course, networked PBXs also require that the customer purchase, install, and maintain separate networks. Still further, it is difficult and expensive to incorporate small clusters of remote extensions/subscribers into a private network. In particularly inefficient cases, it may be necessary to install a separate PBX at a remote location in order to incorporate only a handful of subscribers into the main organization network.
Public telecommunication network operators have attempted to meet the above-described needs using a central office switch service referred to as CENTREX where the functionality of a PBX is emulated by software in the central office switch. However, the CENTREX approach has not met customer requirements with respect to openness and flexibility. For example, the CENTREX solution is restricted to the flexibility and openness provided by the central office switch. Customers typically cannot connect generally available computer application servers, such as CTI servers, to control call and service handling in the central office switch. Another stumbling block for solutions offered by telecommunication network operators is that service development is usually quite slow and rigid due to the centralized nature of public telecommunications networks and ongoing standardization work in that arena.
The present invention solves these problems and meets the needs noted above by integrating services offered by computer application CTI servers from the private network with intelligent network (IN) services offered from the public telecommunications network. In fact, the present invention provides an arrangement and procedures that allow currently available CTI servers designed to work with PBXs to communicate instead with the intelligent network to cooperatively deliver telecommunications services. As a result, the present invention combines the benefits provided by IN-based and CPE-based systems.
More specifically, a telecommunications system in accordance with one example embodiment of the present invention includes a public telecommunications intelligent network (IN) including an IN service control element and an IN service switching control element used to provide IN services following IN control procedures. A private telecommunications network includes a CTI server that provides CTI services following CTI control procedures. A network gateway is provided between the public and private networks and permits the CTI server to request a service from the IN service control element. In an example embodiment of the present invention, this network gateway is referred to as a CTI gateway. The CTI gateway establishes a service logic communications path between a service control function in the IN service control point and a computing function in the CTI server.
A significant advantage of the present invention is that private network telecommunications services can be provided without having to purchase, install, or maintain a PBX or other private switching equipment. Instead, the CTI gateway includes an interface that emulates a private branch exchange switch to receive service communications from the CTI server. This way currently available CTI servers can be implemented without significant modifications or additions. On the intelligent network side, the CTI gateway also includes an IN interface that emulates a public IN node to receive service communications from the IN service control point. Thus, the CTI server requests a service from the CTI gateway using a CTI control protocol, and the IN service control point responds to that service request with the CTI gateway using IN-based protocols, e.g., INAP. The CTI gateway performs the necessary conversions to complete the communications in both directions.
As a result of the present invention, a business or other organization can establish a virtual private network (VPN) using a CTI-type server connected by a network to a plurality of operator workstations, each operator workstation being associated with the telephone. These telephones and other telephones are connected to an intelligent network. Even though there is only one organization, groups of telephone devices may be located in separate geographical locations. Various private network services such as internal private numbering plans, automatic call distribution, call reroutings, etc. may then be provided through the CTI gateway with the assistance of the intelligent network. As a result, the size of the virtual private network is limited only by the size of the intelligent network.
The present invention network therefore provides a method of enhancing telecommunication services offered in a private network controlled using a computer serving a private network using services from an intelligent network. The method includes providing a gateway between the computer server and the service control element of the intelligent network. The computer server requests from the gateway a switching service for the private network. The gateway then conveys a switching message corresponding to the requested switching service to the IN service control element. In response to the switching message, the service control element performs the requested switching function using one or more IN switching elements.
Service logic corresponding to a private network service is established in the IN service control element, and one or more triggering conditions is established in the one or more IN switching elements. When the IN switching element detects a call having a trigger condition, the IN service switching invokes the private network service logic in the IN service control element. The detection of the call and related call information are forwarded and stored in the gateway. That information may be communicated to the computer server in the private network via the gateway. The computer server processes the call information and instructs via the gateway the IN service control element to complete the call. The IN service control element then instructs the IN service switching element to complete the call.
As a result of the present invention, private network extensions/subscribers are not limited to one PBX or to a central office switch, i.e., CENTREX. Instead, the extent of the private network is limited only by the extent of the IN network. In essence, the present invention provides a "virtual" or logical PBX within the intelligent network, and as a result, no switched equipment is needed by customers/organizations. By integrating the services provided by the intelligent network with those provided by private network CTI servers, the variety and sophistication of services that can be ultimately designed and provided to customers is significantly advanced. For example, IN services offer additional capabilities such as handling of large multi-party calls and charging capabilities. Like the switching functionality, other expensive special resource functions may also be centralized and therefore utilized more efficiently.
Additional objects, advantages, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practicing the invention.